/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.feilong.lib.lang3.builder;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import com.feilong.lib.lang3.ArrayUtils;
import com.feilong.lib.lang3.ClassUtils;
import com.feilong.lib.lang3.tuple.Pair;

/**
 * <p>
 * Assists in implementing {@link Object#equals(Object)} methods.
 * </p>
 *
 * <p>
 * This class provides methods to build a good equals method for any
 * class. It follows rules laid out in
 * <a href="http://www.oracle.com/technetwork/java/effectivejava-136174.html">Effective Java</a>
 * , by Joshua Bloch. In particular the rule for comparing {@code doubles},
 * {@code floats}, and arrays can be tricky. Also, making sure that
 * {@code equals()} and {@code hashCode()} are consistent can be
 * difficult.
 * </p>
 *
 * <p>
 * Two Objects that compare as equals must generate the same hash code,
 * but two Objects with the same hash code do not have to be equal.
 * </p>
 *
 * <p>
 * All relevant fields should be included in the calculation of equals.
 * Derived fields may be ignored. In particular, any field used in
 * generating a hash code must be used in the equals method, and vice
 * versa.
 * </p>
 *
 * <p>
 * Typical use for the code is as follows:
 * </p>
 * 
 * <pre>
 * 
 * public boolean equals(Object obj){
 *     if (obj == null){
 *         return false;
 *     }
 *     if (obj == this){
 *         return true;
 *     }
 *     if (obj.getClass() != getClass()){
 *         return false;
 *     }
 *     MyClass rhs = (MyClass) obj;
 *     return new EqualsBuilder().appendSuper(super.equals(obj)).append(field1, rhs.field1).append(field2, rhs.field2)
 *                     .append(field3, rhs.field3).isEquals();
 * }
 * </pre>
 *
 * <p>
 * Alternatively, there is a method that uses reflection to determine
 * the fields to test. Because these fields are usually private, the method,
 * {@code reflectionEquals}, uses {@code AccessibleObject.setAccessible} to
 * change the visibility of the fields. This will fail under a security
 * manager, unless the appropriate permissions are set up correctly. It is
 * also slower than testing explicitly. Non-primitive fields are compared using
 * {@code equals()}.
 * </p>
 *
 * <p>
 * A typical invocation for this method would look like:
 * </p>
 * 
 * <pre>
 * 
 * public boolean equals(Object obj){
 *     return EqualsBuilder.reflectionEquals(this, obj);
 * }
 * </pre>
 *
 * <p>
 * The {@link EqualsExclude} annotation can be used to exclude fields from being
 * used by the {@code reflectionEquals} methods.
 * </p>
 *
 * @since 1.0
 */
public class EqualsBuilder implements Builder<Boolean>{

    /**
     * <p>
     * A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.
     * </p>
     *
     * @since 3.0
     */
    private static final ThreadLocal<Set<Pair<IDKey, IDKey>>> REGISTRY = new ThreadLocal<>();

    /*
     * NOTE: we cannot store the actual objects in a HashSet, as that would use the very hashCode()
     * we are in the process of calculating.
     *
     * So we generate a one-to-one mapping from the original object to a new object.
     *
     * Now HashSet uses equals() to determine if two elements with the same hash code really
     * are equal, so we also need to ensure that the replacement objects are only equal
     * if the original objects are identical.
     *
     * The original implementation (2.4 and before) used the System.identityHashCode()
     * method - however this is not guaranteed to generate unique ids (e.g. LANG-459)
     *
     * We now use the IDKey helper class (adapted from org.apache.axis.utils.IDKey)
     * to disambiguate the duplicate ids.
     */

    /**
     * <p>
     * Returns the registry of object pairs being traversed by the reflection
     * methods in the current thread.
     * </p>
     *
     * @return Set the registry of objects being traversed
     * @since 3.0
     */
    static Set<Pair<IDKey, IDKey>> getRegistry(){
        return REGISTRY.get();
    }

    /**
     * <p>
     * Converters value pair into a register pair.
     * </p>
     *
     * @param lhs
     *            {@code this} object
     * @param rhs
     *            the other object
     *
     * @return the pair
     */
    static Pair<IDKey, IDKey> getRegisterPair(final Object lhs,final Object rhs){
        final IDKey left = new IDKey(lhs);
        final IDKey right = new IDKey(rhs);
        return Pair.of(left, right);
    }

    /**
     * <p>
     * Returns {@code true} if the registry contains the given object pair.
     * Used by the reflection methods to avoid infinite loops.
     * Objects might be swapped therefore a check is needed if the object pair
     * is registered in given or swapped order.
     * </p>
     *
     * @param lhs
     *            {@code this} object to lookup in registry
     * @param rhs
     *            the other object to lookup on registry
     * @return boolean {@code true} if the registry contains the given object.
     * @since 3.0
     */
    static boolean isRegistered(final Object lhs,final Object rhs){
        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
        final Pair<IDKey, IDKey> swappedPair = Pair.of(pair.getRight(), pair.getLeft());

        return registry != null && (registry.contains(pair) || registry.contains(swappedPair));
    }

    /**
     * <p>
     * Registers the given object pair.
     * Used by the reflection methods to avoid infinite loops.
     * </p>
     *
     * @param lhs
     *            {@code this} object to register
     * @param rhs
     *            the other object to register
     */
    private static void register(final Object lhs,final Object rhs){
        Set<Pair<IDKey, IDKey>> registry = getRegistry();
        if (registry == null){
            registry = new HashSet<>();
            REGISTRY.set(registry);
        }
        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
        registry.add(pair);
    }

    /**
     * <p>
     * Unregisters the given object pair.
     * </p>
     *
     * <p>
     * Used by the reflection methods to avoid infinite loops.
     *
     * @param lhs
     *            {@code this} object to unregister
     * @param rhs
     *            the other object to unregister
     * @since 3.0
     */
    private static void unregister(final Object lhs,final Object rhs){
        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
        if (registry != null){
            final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
            registry.remove(pair);
            if (registry.isEmpty()){
                REGISTRY.remove();
            }
        }
    }

    /**
     * If the fields tested are equals.
     * The default value is {@code true}.
     */
    private boolean        isEquals         = true;

    private boolean        testTransients   = false;

    private boolean        testRecursive    = false;

    private List<Class<?>> bypassReflectionClasses;

    private Class<?>       reflectUpToClass = null;

    private String[]       excludeFields    = null;

    /**
     * <p>
     * Constructor for EqualsBuilder.
     * </p>
     *
     * <p>
     * Starts off assuming that equals is {@code true}.
     * </p>
     * 
     * @see Object#equals(Object)
     */
    public EqualsBuilder(){
        // set up default classes to bypass reflection for
        bypassReflectionClasses = new ArrayList<>();
        bypassReflectionClasses.add(String.class); //hashCode field being lazy but not transient
    }

    //-------------------------------------------------------------------------

    /**
     * Set whether to include transient fields when reflectively comparing objects.
     * 
     * @param testTransients
     *            whether to test transient fields
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setTestTransients(final boolean testTransients){
        this.testTransients = testTransients;
        return this;
    }

    /**
     * Set whether to include transient fields when reflectively comparing objects.
     * 
     * @param testRecursive
     *            whether to do a recursive test
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setTestRecursive(final boolean testRecursive){
        this.testRecursive = testRecursive;
        return this;
    }

    /**
     * <p>
     * Set {@code Class}es whose instances should be compared by calling their {@code equals}
     * although being in recursive mode. So the fields of theses classes will not be compared recursively by reflection.
     * </p>
     *
     * <p>
     * Here you should name classes having non-transient fields which are cache fields being set lazily.<br>
     * Prominent example being {@link String} class with its hash code cache field. Due to the importance
     * of the {@code String} class, it is included in the default bypasses classes. Usually, if you use
     * your own set of classes here, remember to include {@code String} class, too.
     * </p>
     * 
     * @param bypassReflectionClasses
     *            classes to bypass reflection test
     * @return EqualsBuilder - used to chain calls.
     * @since 3.8
     */
    public EqualsBuilder setBypassReflectionClasses(final List<Class<?>> bypassReflectionClasses){
        this.bypassReflectionClasses = bypassReflectionClasses;
        return this;
    }

    /**
     * Set the superclass to reflect up to at reflective tests.
     * 
     * @param reflectUpToClass
     *            the super class to reflect up to
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setReflectUpToClass(final Class<?> reflectUpToClass){
        this.reflectUpToClass = reflectUpToClass;
        return this;
    }

    /**
     * Set field names to be excluded by reflection tests.
     * 
     * @param excludeFields
     *            the fields to exclude
     * @return EqualsBuilder - used to chain calls.
     * @since 3.6
     */
    public EqualsBuilder setExcludeFields(final String...excludeFields){
        this.excludeFields = excludeFields;
        return this;
    }

    /**
     * <p>
     * This method uses reflection to determine if the two {@code Object}s
     * are equal.
     * </p>
     *
     * <p>
     * It uses {@code AccessibleObject.setAccessible} to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly. Non-primitive fields are compared using
     * {@code equals()}.
     * </p>
     *
     * <p>
     * Transient members will be not be tested, as they are likely derived
     * fields, and not part of the value of the Object.
     * </p>
     *
     * <p>
     * Static fields will not be tested. Superclass fields will be included.
     * </p>
     *
     * @param lhs
     *            {@code this} object
     * @param rhs
     *            the other object
     * @param excludeFields
     *            Collection of String field names to exclude from testing
     * @return {@code true} if the two Objects have tested equals.
     *
     * @see EqualsExclude
     */
    public static boolean reflectionEquals(final Object lhs,final Object rhs,final Collection<String> excludeFields){
        return reflectionEquals(lhs, rhs, ReflectionToStringBuilder.toNoNullStringArray(excludeFields));
    }

    /**
     * <p>
     * This method uses reflection to determine if the two {@code Object}s
     * are equal.
     * </p>
     *
     * <p>
     * It uses {@code AccessibleObject.setAccessible} to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly. Non-primitive fields are compared using
     * {@code equals()}.
     * </p>
     *
     * <p>
     * Transient members will be not be tested, as they are likely derived
     * fields, and not part of the value of the Object.
     * </p>
     *
     * <p>
     * Static fields will not be tested. Superclass fields will be included.
     * </p>
     *
     * @param lhs
     *            {@code this} object
     * @param rhs
     *            the other object
     * @param excludeFields
     *            array of field names to exclude from testing
     * @return {@code true} if the two Objects have tested equals.
     *
     * @see EqualsExclude
     */
    public static boolean reflectionEquals(final Object lhs,final Object rhs,final String...excludeFields){
        return reflectionEquals(lhs, rhs, false, null, excludeFields);
    }

    /**
     * <p>
     * This method uses reflection to determine if the two {@code Object}s
     * are equal.
     * </p>
     *
     * <p>
     * It uses {@code AccessibleObject.setAccessible} to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly. Non-primitive fields are compared using
     * {@code equals()}.
     * </p>
     *
     * <p>
     * If the TestTransients parameter is set to {@code true}, transient
     * members will be tested, otherwise they are ignored, as they are likely
     * derived fields, and not part of the value of the {@code Object}.
     * </p>
     *
     * <p>
     * Static fields will not be tested. Superclass fields will be included.
     * </p>
     *
     * @param lhs
     *            {@code this} object
     * @param rhs
     *            the other object
     * @param testTransients
     *            whether to include transient fields
     * @return {@code true} if the two Objects have tested equals.
     *
     * @see EqualsExclude
     */
    public static boolean reflectionEquals(final Object lhs,final Object rhs,final boolean testTransients){
        return reflectionEquals(lhs, rhs, testTransients, null);
    }

    /**
     * <p>
     * This method uses reflection to determine if the two {@code Object}s
     * are equal.
     * </p>
     *
     * <p>
     * It uses {@code AccessibleObject.setAccessible} to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly. Non-primitive fields are compared using
     * {@code equals()}.
     * </p>
     *
     * <p>
     * If the testTransients parameter is set to {@code true}, transient
     * members will be tested, otherwise they are ignored, as they are likely
     * derived fields, and not part of the value of the {@code Object}.
     * </p>
     *
     * <p>
     * Static fields will not be included. Superclass fields will be appended
     * up to and including the specified superclass. A null superclass is treated
     * as java.lang.Object.
     * </p>
     *
     * @param lhs
     *            {@code this} object
     * @param rhs
     *            the other object
     * @param testTransients
     *            whether to include transient fields
     * @param reflectUpToClass
     *            the superclass to reflect up to (inclusive),
     *            may be {@code null}
     * @param excludeFields
     *            array of field names to exclude from testing
     * @return {@code true} if the two Objects have tested equals.
     *
     * @see EqualsExclude
     * @since 2.0
     */
    public static boolean reflectionEquals(
                    final Object lhs,
                    final Object rhs,
                    final boolean testTransients,
                    final Class<?> reflectUpToClass,
                    final String...excludeFields){
        return reflectionEquals(lhs, rhs, testTransients, reflectUpToClass, false, excludeFields);
    }

    /**
     * <p>
     * This method uses reflection to determine if the two {@code Object}s
     * are equal.
     * </p>
     *
     * <p>
     * It uses {@code AccessibleObject.setAccessible} to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly. Non-primitive fields are compared using
     * {@code equals()}.
     * </p>
     *
     * <p>
     * If the testTransients parameter is set to {@code true}, transient
     * members will be tested, otherwise they are ignored, as they are likely
     * derived fields, and not part of the value of the {@code Object}.
     * </p>
     *
     * <p>
     * Static fields will not be included. Superclass fields will be appended
     * up to and including the specified superclass. A null superclass is treated
     * as java.lang.Object.
     * </p>
     *
     * <p>
     * If the testRecursive parameter is set to {@code true}, non primitive
     * (and non primitive wrapper) field types will be compared by
     * {@code EqualsBuilder} recursively instead of invoking their
     * {@code equals()} method. Leading to a deep reflection equals test.
     *
     * @param lhs
     *            {@code this} object
     * @param rhs
     *            the other object
     * @param testTransients
     *            whether to include transient fields
     * @param reflectUpToClass
     *            the superclass to reflect up to (inclusive),
     *            may be {@code null}
     * @param testRecursive
     *            whether to call reflection equals on non primitive
     *            fields recursively.
     * @param excludeFields
     *            array of field names to exclude from testing
     * @return {@code true} if the two Objects have tested equals.
     *
     * @see EqualsExclude
     * @since 3.6
     */
    public static boolean reflectionEquals(
                    final Object lhs,
                    final Object rhs,
                    final boolean testTransients,
                    final Class<?> reflectUpToClass,
                    final boolean testRecursive,
                    final String...excludeFields){
        if (lhs == rhs){
            return true;
        }
        if (lhs == null || rhs == null){
            return false;
        }
        return new EqualsBuilder().setExcludeFields(excludeFields).setReflectUpToClass(reflectUpToClass).setTestTransients(testTransients)
                        .setTestRecursive(testRecursive).reflectionAppend(lhs, rhs).isEquals();
    }

    /**
     * <p>
     * Tests if two {@code objects} by using reflection.
     * </p>
     *
     * <p>
     * It uses {@code AccessibleObject.setAccessible} to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly. Non-primitive fields are compared using
     * {@code equals()}.
     * </p>
     *
     * <p>
     * If the testTransients field is set to {@code true}, transient
     * members will be tested, otherwise they are ignored, as they are likely
     * derived fields, and not part of the value of the {@code Object}.
     * </p>
     *
     * <p>
     * Static fields will not be included. Superclass fields will be appended
     * up to and including the specified superclass in field {@code reflectUpToClass}.
     * A null superclass is treated as java.lang.Object.
     * </p>
     *
     * <p>
     * Field names listed in field {@code excludeFields} will be ignored.
     * </p>
     *
     * <p>
     * If either class of the compared objects is contained in
     * {@code bypassReflectionClasses}, both objects are compared by calling
     * the equals method of the left hand object with the right hand object as an argument.
     * </p>
     *
     * @param lhs
     *            the left hand object
     * @param rhs
     *            the left hand object
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder reflectionAppend(final Object lhs,final Object rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            isEquals = false;
            return this;
        }

        // Find the leaf class since there may be transients in the leaf
        // class or in classes between the leaf and root.
        // If we are not testing transients or a subclass has no ivars,
        // then a subclass can test equals to a superclass.
        final Class<?> lhsClass = lhs.getClass();
        final Class<?> rhsClass = rhs.getClass();
        Class<?> testClass;
        if (lhsClass.isInstance(rhs)){
            testClass = lhsClass;
            if (!rhsClass.isInstance(lhs)){
                // rhsClass is a subclass of lhsClass
                testClass = rhsClass;
            }
        }else if (rhsClass.isInstance(lhs)){
            testClass = rhsClass;
            if (!lhsClass.isInstance(rhs)){
                // lhsClass is a subclass of rhsClass
                testClass = lhsClass;
            }
        }else{
            // The two classes are not related.
            isEquals = false;
            return this;
        }

        try{
            if (testClass.isArray()){
                append(lhs, rhs);
            }else{
                //If either class is being excluded, call normal object equals method on lhsClass.
                if (bypassReflectionClasses != null
                                && (bypassReflectionClasses.contains(lhsClass) || bypassReflectionClasses.contains(rhsClass))){
                    isEquals = lhs.equals(rhs);
                }else{
                    reflectionAppend(lhs, rhs, testClass);
                    while (testClass.getSuperclass() != null && testClass != reflectUpToClass){
                        testClass = testClass.getSuperclass();
                        reflectionAppend(lhs, rhs, testClass);
                    }
                }
            }
        }catch (final IllegalArgumentException e){
            // In this case, we tried to test a subclass vs. a superclass and
            // the subclass has ivars or the ivars are transient and
            // we are testing transients.
            // If a subclass has ivars that we are trying to test them, we get an
            // exception and we know that the objects are not equal.
            isEquals = false;
            return this;
        }
        return this;
    }

    /**
     * <p>
     * Appends the fields and values defined by the given object of the
     * given Class.
     * </p>
     *
     * @param lhs
     *            the left hand object
     * @param rhs
     *            the right hand object
     * @param clazz
     *            the class to append details of
     */
    private void reflectionAppend(final Object lhs,final Object rhs,final Class<?> clazz){

        if (isRegistered(lhs, rhs)){
            return;
        }

        try{
            register(lhs, rhs);
            final Field[] fields = clazz.getDeclaredFields();
            AccessibleObject.setAccessible(fields, true);
            for (int i = 0; i < fields.length && isEquals; i++){
                final Field f = fields[i];
                if (!ArrayUtils.contains(excludeFields, f.getName()) && !f.getName().contains("$")
                                && (testTransients || !Modifier.isTransient(f.getModifiers())) && !Modifier.isStatic(f.getModifiers())
                                && !f.isAnnotationPresent(EqualsExclude.class)){
                    try{
                        append(f.get(lhs), f.get(rhs));
                    }catch (final IllegalAccessException e){
                        //this can't happen. Would get a Security exception instead
                        //throw a runtime exception in case the impossible happens.
                        throw new InternalError("Unexpected IllegalAccessException");
                    }
                }
            }
        }finally{
            unregister(lhs, rhs);
        }
    }

    //-------------------------------------------------------------------------

    /**
     * <p>
     * Adds the result of {@code super.equals()} to this builder.
     * </p>
     *
     * @param superEquals
     *            the result of calling {@code super.equals()}
     * @return EqualsBuilder - used to chain calls.
     * @since 2.0
     */
    public EqualsBuilder appendSuper(final boolean superEquals){
        if (!isEquals){
            return this;
        }
        isEquals = superEquals;
        return this;
    }

    //-------------------------------------------------------------------------

    /**
     * <p>
     * Test if two {@code Object}s are equal using either
     * #{@link #reflectionAppend(Object, Object)}, if object are non
     * primitives (or wrapper of primitives) or if field {@code testRecursive}
     * is set to {@code false}. Otherwise, using their
     * {@code equals} method.
     * </p>
     *
     * @param lhs
     *            the left hand object
     * @param rhs
     *            the right hand object
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final Object lhs,final Object rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        final Class<?> lhsClass = lhs.getClass();
        if (lhsClass.isArray()){
            // factor out array case in order to keep method small enough
            // to be inlined
            appendArray(lhs, rhs);
        }else{
            // The simple case, not an array, just test the element
            if (testRecursive && !ClassUtils.isPrimitiveOrWrapper(lhsClass)){
                reflectionAppend(lhs, rhs);
            }else{
                isEquals = lhs.equals(rhs);
            }
        }
        return this;
    }

    /**
     * <p>
     * Test if an {@code Object} is equal to an array.
     * </p>
     *
     * @param lhs
     *            the left hand object, an array
     * @param rhs
     *            the right hand object
     */
    private void appendArray(final Object lhs,final Object rhs){
        // First we compare different dimensions, for example: a boolean[][] to a boolean[]
        // then we 'Switch' on type of array, to dispatch to the correct handler
        // This handles multi dimensional arrays of the same depth
        if (lhs.getClass() != rhs.getClass()){
            this.setEquals(false);
        }else if (lhs instanceof long[]){
            append((long[]) lhs, (long[]) rhs);
        }else if (lhs instanceof int[]){
            append((int[]) lhs, (int[]) rhs);
        }else if (lhs instanceof short[]){
            append((short[]) lhs, (short[]) rhs);
        }else if (lhs instanceof char[]){
            append((char[]) lhs, (char[]) rhs);
        }else if (lhs instanceof byte[]){
            append((byte[]) lhs, (byte[]) rhs);
        }else if (lhs instanceof double[]){
            append((double[]) lhs, (double[]) rhs);
        }else if (lhs instanceof float[]){
            append((float[]) lhs, (float[]) rhs);
        }else if (lhs instanceof boolean[]){
            append((boolean[]) lhs, (boolean[]) rhs);
        }else{
            // Not an array of primitives
            append((Object[]) lhs, (Object[]) rhs);
        }
    }

    /**
     * <p>
     * Test if two {@code long} s are equal.
     * </p>
     *
     * @param lhs
     *            the left hand {@code long}
     * @param rhs
     *            the right hand {@code long}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final long lhs,final long rhs){
        if (!isEquals){
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    /**
     * <p>
     * Test if two {@code int}s are equal.
     * </p>
     *
     * @param lhs
     *            the left hand {@code int}
     * @param rhs
     *            the right hand {@code int}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final int lhs,final int rhs){
        if (!isEquals){
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    /**
     * <p>
     * Test if two {@code short}s are equal.
     * </p>
     *
     * @param lhs
     *            the left hand {@code short}
     * @param rhs
     *            the right hand {@code short}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final short lhs,final short rhs){
        if (!isEquals){
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    /**
     * <p>
     * Test if two {@code char}s are equal.
     * </p>
     *
     * @param lhs
     *            the left hand {@code char}
     * @param rhs
     *            the right hand {@code char}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final char lhs,final char rhs){
        if (!isEquals){
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    /**
     * <p>
     * Test if two {@code byte}s are equal.
     * </p>
     *
     * @param lhs
     *            the left hand {@code byte}
     * @param rhs
     *            the right hand {@code byte}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final byte lhs,final byte rhs){
        if (!isEquals){
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    /**
     * <p>
     * Test if two {@code double}s are equal by testing that the
     * pattern of bits returned by {@code doubleToLong} are equal.
     * </p>
     *
     * <p>
     * This handles NaNs, Infinities, and {@code -0.0}.
     * </p>
     *
     * <p>
     * It is compatible with the hash code generated by
     * {@code HashCodeBuilder}.
     * </p>
     *
     * @param lhs
     *            the left hand {@code double}
     * @param rhs
     *            the right hand {@code double}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final double lhs,final double rhs){
        if (!isEquals){
            return this;
        }
        return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
    }

    /**
     * <p>
     * Test if two {@code float}s are equal by testing that the
     * pattern of bits returned by doubleToLong are equal.
     * </p>
     *
     * <p>
     * This handles NaNs, Infinities, and {@code -0.0}.
     * </p>
     *
     * <p>
     * It is compatible with the hash code generated by
     * {@code HashCodeBuilder}.
     * </p>
     *
     * @param lhs
     *            the left hand {@code float}
     * @param rhs
     *            the right hand {@code float}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final float lhs,final float rhs){
        if (!isEquals){
            return this;
        }
        return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
    }

    /**
     * <p>
     * Test if two {@code booleans}s are equal.
     * </p>
     *
     * @param lhs
     *            the left hand {@code boolean}
     * @param rhs
     *            the right hand {@code boolean}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final boolean lhs,final boolean rhs){
        if (!isEquals){
            return this;
        }
        isEquals = lhs == rhs;
        return this;
    }

    /**
     * <p>
     * Performs a deep comparison of two {@code Object} arrays.
     * </p>
     *
     * <p>
     * This also will be called for the top level of
     * multi-dimensional, ragged, and multi-typed arrays.
     * </p>
     *
     * <p>
     * Note that this method does not compare the type of the arrays; it only
     * compares the contents.
     * </p>
     *
     * @param lhs
     *            the left hand {@code Object[]}
     * @param rhs
     *            the right hand {@code Object[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final Object[] lhs,final Object[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code long}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(long, long)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code long[]}
     * @param rhs
     *            the right hand {@code long[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final long[] lhs,final long[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code int}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(int, int)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code int[]}
     * @param rhs
     *            the right hand {@code int[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final int[] lhs,final int[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code short}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(short, short)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code short[]}
     * @param rhs
     *            the right hand {@code short[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final short[] lhs,final short[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code char}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(char, char)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code char[]}
     * @param rhs
     *            the right hand {@code char[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final char[] lhs,final char[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code byte}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(byte, byte)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code byte[]}
     * @param rhs
     *            the right hand {@code byte[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final byte[] lhs,final byte[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code double}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(double, double)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code double[]}
     * @param rhs
     *            the right hand {@code double[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final double[] lhs,final double[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code float}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(float, float)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code float[]}
     * @param rhs
     *            the right hand {@code float[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final float[] lhs,final float[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Deep comparison of array of {@code boolean}. Length and all
     * values are compared.
     * </p>
     *
     * <p>
     * The method {@link #append(boolean, boolean)} is used.
     * </p>
     *
     * @param lhs
     *            the left hand {@code boolean[]}
     * @param rhs
     *            the right hand {@code boolean[]}
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final boolean[] lhs,final boolean[] rhs){
        if (!isEquals){
            return this;
        }
        if (lhs == rhs){
            return this;
        }
        if (lhs == null || rhs == null){
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length){
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i){
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>
     * Returns {@code true} if the fields that have been checked
     * are all equal.
     * </p>
     *
     * @return boolean
     */
    public boolean isEquals(){
        return this.isEquals;
    }

    /**
     * <p>
     * Returns {@code true} if the fields that have been checked
     * are all equal.
     * </p>
     *
     * @return {@code true} if all of the fields that have been checked
     *         are equal, {@code false} otherwise.
     *
     * @since 3.0
     */
    @Override
    public Boolean build(){
        return Boolean.valueOf(isEquals());
    }

    /**
     * Sets the {@code isEquals} value.
     *
     * @param isEquals
     *            The value to set.
     * @since 2.1
     */
    protected void setEquals(final boolean isEquals){
        this.isEquals = isEquals;
    }

    /**
     * Reset the EqualsBuilder so you can use the same object again
     * 
     * @since 2.5
     */
    public void reset(){
        this.isEquals = true;
    }
}
